1. Field of the Invention
The present invention relates to a saturated polyester resin bottle, which has its parison oriented not only at its barrel but also at its mouth, and to a method for producing the same.
2. Description of the Prior Art
A bottle of a saturated polyester resin is known to be free from exudation of a solvent or the like and from generation of poinsonous gases, when it is burned after it is disposed, and to be excellent in its durability. However, these excellent properties and durability of the saturated polyester resin can be exhibited only in case the article made of the saturated polyester resin is subjected to an orienting treatment.
Bottles of saturated polyester resin are produced, from a parison of tubular material prepared by an injection-molding process which is then oriented before it is blow-molded into the desired bottle shape.
The blow-molding of the parison, is performed only at the barrel of the parison while the mouth of the parison is held in a mold therefor. As a result, the barrel of the product bottle has been subjected to the orienting treatment whereas the mouth of the same is left unoriented.
Thus, the bottle barrel exhibits the excellent properties and durability intrinsic to the saturated polyester resin to a sufficient extent whereas the bottle mouth fails to sufficiently exhibit those excellent properties. For instance, if the bottle is wetted with alcohol of high concentration, this alcohol will penetrate so deeply into the mouth as to whiten and mechanically weaken the mouth and to produce a number of fine cracks which deteriorate the sealing effects of the mouth.